Conventionally, a fingerprint detection circuit comprising a sensor capacitor is used to detect fingerprints lying on the fingerprint detection circuit.
When no finger lies on the fingerprint detection circuit, as illustrated in FIG. 1, a stable electric field is formed between a first terminal C1 of a sensor capacitor C and a second terminal C2 thereof. When a finger lies on the fingerprint detection circuit, a quantity of electricity stored in the sensor capacitor will be changed, thereby changing a current output by the fingerprint detection circuit. Valleys and ridges of the fingerprint have different influence on the sensor capacitor. As a result, the morphology of the fingerprint is determined by the amount of change of the current.
However, the conventional fingerprint detection circuit cannot identify morphology of fingerprints precisely.